Investigations of radiation resistant beryllium grades for nuclear fusion applications

R&D results on beryllium with high radiation resistance obtained recently are described in this report. The data are presented on nine different grades of isotropic beryllium manufactured by VNIINM and distinguished by both initial powder characteristics and properties of billets, made of these powders. The average grain size of the investigated beryllium grades varied from 8 to 26 μm, the content of beryllium oxide was 0.9-3.9 wt.%, the dispersity of beryllium oxide ~0.04-0.5 μm, tensile strength-250-650 MPa. All materials were irradiated in SM-2 reactor over the temperature range 550-780°C. The results of the investigation showed, that HIP beryllium grades are less susceptible to swelling at higher temperatures in comparison with hot pressed and extruded grades. Beryllium samples, having the smallest grain size, demonstrated minimal swelling, which was less than 0.8% at 750°C and Fs=3.7·10²¹ cm^-2 (E>0.1 MeV). The mechanical properties, creep and microstructure parameters, measured before and after irradiation, are presented